1. Field of the Invention
The present invention relates to a chucking device, a motor, a disk drive apparatus and a chucking device manufacturing method.
2. Description of the Related Art
A brushless motor for rotating a disk is mounted to a disk drive apparatus such as an optical disk drive or the like. The brushless motor includes a chucking device rotating together with a rotary unit. The disk drive apparatus causes rotation of the disk by driving the brushless motor while keeping the disk held with the chucking device.
In recent years, the rotation speed of a brushless motor tends to become higher along with the increase in the operation speed of a disk drive apparatus. If the brushless motor rotates faster, vibration is likely to occur during operation of the brushless motor. One of causes of the vibration generated in the brushless motor is the deviation in the gravity center of a disk. The position of the gravity center of a disk differs slightly from disk to disk. The vibration at issue is prone to occur in the event that the gravity center of the rotary unit and the disk as a whole does not coincide with the rotation center of the brushless motor.
Conventionally, as one example of the techniques for correcting the deviation in the gravity center, a motor in which a plurality of balls as balancing bodies is accommodated within an annular space defined between a positioning member having a U-shape in cross section and a turntable of a rotor. As another example, a motor in which a plurality of balls as balancing bodies is movably arranged within an annular movement space defined by a case body and a cover arranged in the upper space inside a rotor body. In the conventional structures, attempts are made to eliminate weight unbalance by moving the balls as balancing bodies during high-speed rotation.
In the conventional structures, press-fit or adhesive fixing is used as a method of fixing the positioning member or the case body to the rotor or the rotor body. Use of either the press-fit or the adhesive fixing can achieve the fixing strength generally required in a brushless motor. In order to provide a brushless motor of higher quality, there is a need to further enhance the fixing strength. Further, there is a need to restrain the noises generated by the rolling movement of balls.